Computerized tomography imaging systems and position-tracking systems may be used in various medical applications, such as image guided procedures.
For example, U.S. Pat. No. 6,560,354, whose disclosure is incorporated herein by reference, describes apparatus and method for registration of images to physical space using a weighted combination of points and surfaces. An image of a patient taken through X-ray computed tomography is registered to physical measurements taken on the patient's body. Different parts of the patient's body are given different numerical weights; for example, if bone measurements are deemed to be more accurate than skin measurements, the bones can be given a higher weight than the skin. The weights are used in an iterative registration process to determine a rigid body transformation function.
U.S. Pat. No. 8,271,068, whose disclosure is incorporated herein by reference, describes a method of determining a three-dimensional (3D) position of a catheter tip that includes: compensating a two-dimensional (2D) position of the tip of the catheter for respiratory motion to generate a compensated 2D catheter position, generating weighted sample points around the compensated 2D catheter position, determining correspondent points of the weighted sample points in a 3D image, computing a weighted mean and a weighted covariance of each correspondent point, and determining the 3D position of the catheter tip in the 3D image from a fusion of the weighted means and weighted covariance.